Assessment of the feasibility of mouthpiece-mediated aerosol delivery during high flow nasal therapy.
Ian MacDonnacha, Gavin Bennett, Sorcha Murphy, Mary Joyce, Louise Sweeney & Ronan MacLoughlin
Aerogen, Galway Business Park, Dangan, Galway, Ireland
High Flow Nasal Therapy (HFNT) is increasingly used with patients requiring supplementary oxygen. Some patients receiving these therapies may also benefit from inhaled drug delivery. Typically, HFNT systems facilitate simple connection of a nebuliser by means of standardised ISO5356 connections. However, some HFNT systems do not allow for connection of a nebuliser. In these instances, aerosol therapy may be facilitated by placing a facemask over the nasal cannula, however, delivery efficiency is noted to be low.  Aerosol delivery facilitated by the concurrent use of a mouthpiece during HFNT has not yet been described.
This purpose of this study was to address this gap in our knowledge. Delivery was characterised in a simulated spontaneously breathing adult. Combinations of HFNT gas flow rates (10, 30 & 45LPM) (Airvo 2, Fisher & Paykel) and supplemental gas flow rates via a mouthpiece (2, 6LPM) (Aerogen Ultra, Aerogen, Ireland) with a previously described adult head model (LUCY) were assessed. Tracheal dose (a predictor of the expected lung dose) was characterised by quantifying the mass of drug captured on a filter positioned distal to oropharyngeal region.
Increasing HFNT gas flow rates were associated with a decreased tracheal dose. HFNT gas flow rates of 30 & 45 LPM facilitate a tracheal dose below <2% for the mouthpiece flow rates (2 & 6LPM). A HFNT gas flow rate of 10 LPM facilitates a higher tracheal dose. Increasing gas flow rates through the nebuliser were associated with an increased tracheal dose, with 11.02% at 2LPM and 22.06% at 6LPM.